Attachment plug and receptacle



June 4, 1935. w. K. MEss 2,003,943

ATTACHMENT PLUG AND RECEPTACLE Filed' March 12, 1934 l i l INVENTOR W/LBUR K. M555 MSW A Ol-QNEY Patented June 4, 1935 UNITED STATES PATENT OFFICE -3 Claiiris.-

, 'I'he general objects )of this invention are to provide a combination of attachment plug and receptacle, which will be inexpensive, easily manuiactured, assembled and installed, in which the current carrying parts will be well-insulated and the device therefore safe in use.

In the usual combination, care must be exercised to bring the projecting blades of the plug into register with the spaced slots in the receptacle, making itdiflicult to use such apparatus in the dark or in out of the way places. These blades also have a tendency to bind in thereceptacle and prevent the plug from coming loose with pull on the cord as intended with connectors of this type.

Special objects of the present invention are to overcome the latter objections and to provide a combination structure in which the plug may be properly engaged with the receptacle in all angularly or relatively rotatedpositions of the plug and in which the plug may be rotated in the receptacle and readily come away from the recep1 tacle by pull on the cord.

The foregoing and other desirable objects are attained by the novel features of construction hereinafter described and claimed and illustrated in the accompanying drawing.

In the drawing, the invention is shown embodied in one vpractical preferred form, but it is to be understood that the actual physical structure may be modified as regards this disclosure, all within the true intent and broad scope of the claims'.

Fig. 1 is a face view of a double receptacle such v as mounted in a wall box.

Fig. is an enlarged broken vertical sectional view on line 2-2 of Fig. 1 and showing the e and plug in combination. an end view of the plug member of the non. is a broken rear elevation of the double receptacle. Fig. is a longitudinal sectional view of an adapter base for accommodating the plug to a screw socket type of receptacle.

The receptacle illustrated consists of a single unitary base of insulating material `having the somewhat rounded enlargements 6, at opposite ends connected by a reduced intermediate portion l.

At the exposed face of the receptacle base are conical depressions 8, providing access through reduced passages 9, to center receptacle terminals .IILl

The latter are illustrated as cupped split spring members of generally globular shape with reentrant bends I I, and outwardly and backwardly bent ends I2. These spring cups are of a size to be forced forwardly through the passages I3, in back of the base and to thereupon enlarge or spring outwardly into enlargements I4', with the rearwardly bent portions I2 interlocked with shoulders I5.

In the double type receptacle such as illustrated,

the center contacts last described may be connected by a bar I6, and the latter may have a bent up lug Il, lying at one side of the reduced intermediate portion of the base and carrying a terminal screw I8.

Surrounding the center conical cavity of the receptacle is a narrow concentric groove I9, and extending into'thjs groove at one or more points is the outer contact 20.

In the double receptacle shown, the two outer contacts are in the form of .angularly bent lugs on opposite ends of a bar member 2l.

This double contact member, like the other is held in place by introverted or backwardly bent portions 22, at the ends of the contact lugs engaging undercut shoulders 23. These contacts therefore can be secured in position by simply forcing them through the holes 24, in the back of the base until the bent spring ends 22, snap in front of the holding shoulders 23.

As shown in Fig. l, the side 'contacts 20 are preferably rounded substantially to the curvature of the annular slots I9, so as to snugly engage the ring contacts on the plugs which enter these slots. U I

The plug member is shown in the form of .a

substantially iflat disc 25, carrying a projecting' ring contact 26, to fit in the annular slot oi the receptacle and frictionally-engage the curved contact lug 20. The exposed edge of this ring is shown as beveled at 21, to cut its way past dust or other possible obstruction in the annular groove and force back the curved spring contact, substantially Aas shown at the top in Fig. 2.

Projecting from the center of the insulating disc in concentric relation to the ring contact is a center contact stud 28, having a rounded nose 2Q, to pass through the central guide opening 9, into the spring contact socket at the back of the same. l

'I'he center plug c ntact is longer than the ring contact, so that it may be used as a guide pin entering the conical socket 8 of the receptacle and sliding on through the central guide passage 9, to thereby bring the ring contact into position for register with the" annular groove` and into engagement with the side contact 20, extending into.

said groove.

The center and side contacts of the plug may vbe secured by knurling or roughening the same b as indicated at 30, and by molding the plug base about the same.

The ring-contact may be cut from tubing or be made from strip stock vrolled into vcircular form, with-the ends secured together or not, in accordance with the desired stiiness or springincssto be given thel contact. In Fig. 2, the material of the 'ring contact is shown doubled back upon itself at 3I, at the back of the plug, to provide lsufficient thickness for the screw seat 32, taking the terminal screw 33, for one of the wires of the electric cord 34. y

The center plug contact is shown as drilled or otherwise constructed asv hollow from the back having a single terminal lug 40, extended from one side of the connecting bar 2l, andvbent up at the side of the narrow portion of the receptacle base opposite the rst terminal lug I1. Lug 40 is shown as carrying the terminal screw 4I.

This and the other terminal screw I8 .are indicated as extending into holes 42, molded in the sides of the base, these screws then serving as additional means to prevent the contacts coming away from the receptacle base.

A yoke 43 is indicated in Figs. 1 and 2 for mounting the receptacle in the box 44, and this yoke also is held to the receptacle base without screws by making it with punched in lugs 45, in the side arms of the same entering corresponding openings 46, molded in the ends of the base. The side arms 'of this yoke are shown angled or offset at 41, to stand inv back of the end corners of the receptacle base and thereby solidly support the base apart from the support afforded by the lugs 45.

In order that the new plug may be used with existing receptacles of the standard screw socket type, adapters such as indicated in Fig. 5 may be employed, the same being constructed with the conical guide sockets and other features of the new receptacles described, Ybut having screw terminals 48 and centercontacts 49, for cooperof the plug to the center spring contact- I0 and for locating the ring contact 26 with respect to the annular groove I9' and the side contact 20' the receptacle' until the prong enters theconical` depression, whereupon a straight inward push will. then suiiice to solidly couple the contacts.

The glove fastener type of center contact in the receptacle resilientlyholds the plug in position, but a pull on the cord from practically any angle is effective to disconnect theplug from the service contacts.l The receptacle .parts can be assembled by simply pushing the side and center contacts through from the back of the base so that they snap over the holding shoulders 23 and I5. The binding screws I8 and 4 I when turned into the openings 42 in the sides of the base, lock these contact elements in their previously secured relation. These terminal screws may have screw seats in the angled lugs I1 and 4!! of the' contact members, or if desired, these screw seats may be provided by metallic inserts 50, molded or otherwise xed in the sides of the base member. The mounting yoke 43 may be engaged by forcing it over the back of the base until the projections 45 thereon snap into the recesses 46. in the ends of the base. Then when the yoke is mounted in the box andheld against spreading by the securing screws 5I, Fig. 1, the yoke will be held interiocked with the base, so that one can not come away from the other.

The entire structure is simple and inexpensive, easily assembled, practical and safe and ac- Y complishes the objects intended. The structure is susceptible of modification in various ways as will be apparent from the scope of the following claims. Such modiiications may include reversal of -parts and the like, for instance, the ring contact member might be mounted on the receptacle part instead of on the attachment plug part.

What is claimed is:

1. An electric receptacle base having a ilush face with a generally conical prong guiding recess therein, a guide passage /extending back from said recess, a larger chamber at the back of said guide passage and an annular groove in the iiush face portion surrounding the conical recess,

'and contacts located respectively in said chamber and annular groove, said chamber and annular groove being open through to the back of the base, said contacts being entered from the back of the base into said chamber and groove respectively, said chamber. and groove having shoulders v and said contacts f'having resilient locking portions engaging over said shoulders.

2..Anelectric Ireceptacle, comprising 'a base' having substantially circular end portions connected by a narrower neck portion, said base having prongguidng sockets in the face of the' same concentric with said generally cylindrical portions and annular recesses about said prong guidingsocke'ts, contacts entered in said annular recesses and connected by a bar having a terminal lug atene side of the narrower neck portion of the base and center contacts in line with the guide sockets and connected by a bar` having a terminal lug disposed at the opposite side of the narroweneck portion of the base.

3. An"`electric receptacle, comprising a base structure having a substantially iiush face with spaced generally conical prong guiding sockets and concentric annular grooves about said sockets, prong receiving center contacts on the base 'at the back of said prong guiding sockets, a short terminal bar connecting said center contacts and provided with terminal means, a shorter terminal bar on the back of the basextending between the closest portions of the annular grooves and provided with terminal means and side contact elements connected withl the ends of said shorter bar-and disposed in said nearest portions of said annular grooves.

, WILBUR K. MESS. 

